The NEA Committee for the Safety of Nuclear Installations (CSNI) has been promoting international initiatives and collaborations to establish convincing experimental safety programmes around specific facilities. As a first step in this direction, the PKL (Pressurised Water Reactor) loop in Germany and the PANDA in Switzerland were requested to develop proposals consistent with the priorities indicated in the CSNI Senior Group of Experts on Safety Research (SESAR) report Nuclear Safety Research in OECD Countries: Summary Report of Major Facilities and Programmes at Risk. Their proposals, after discussions with Member country experts, formed the basis for the SETH Project.

The SETH Project covers two aspects of accident management:

Part 1 is related to gas mixing and stratification issues in LWR containments under accidental conditions. The experiments have been performed in the PANDA facility at PSI, Switzerland.

Part 2 is related to two PWR safety issues: boron dilution during SB-LOCA and loss of residual heat removal during mid-loop operation. The experiments have been performed in the PKL facility at AREVA NP, Germany. (see also http://www.nea.fr/html/jointproj/pkl-1.html)

The PSI/PANDA experiments provide data on containment three-dimensional gas flow and distribution issues that are important for code prediction capability improvements, accident management and design of mitigating measures. These experiments were conducted on a large scale in multi-compartment geometries in order to provide data suitable for the improvement and validation of safety analysis codes.